Microalgae Aurantiochytrium sp. LA3 (KCTC12685BP) and Method for Preparing Bio-Oil Using the Same

ABSTRACT

Provided herein are microalgae of a Thraustochytrid and a method for preparing bio-oil using the same, and more particularly,  Aurantiochytrium  sp. LA3 (KCTC12685BP) having bio-oil producibility, and a method of preparing bio-oil, particularly bio-oil having a content of omega-3 unsaturated fatty acids of 30% by weight or more based on total fatty acids, characterized by culturing the microalgae. The microalgae  Aurantiochytrium  sp. LA3 (KCTC12685BP) described herein has a rapid sugar consumption rate when being cultured using glucose as a carbon source, has a high oil content, allows cells to be cultured at a high concentration, and allows oil to be obtained in high productivity and a high yield, and thus, may produce bio-oil more economically and environmentally friendly.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority as a divisional application to U.S.patent application Ser. No. 14/813,689 filed Jul. 30, 2015, which claimspriority to Korean Patent Application No. 10-2014-0135586 filed Oct. 8,2014, the disclosures of which are each incorporated in their entiretyby reference.

The Sequence Listing associated with this application is filed inelectronic format via EFS-Web and is hereby incorporated by referenceinto the specification in its entirety. The name of the text filecontaining the Sequence Listing is 155686_ST25.txt. The size of the textfile is 2,076 bytes, and the text file was created on Jul. 28, 2015.

TECHNICAL FIELD

The present invention relates to microalgae of a Thraustochytrid and amethod for preparing bio-oil using the same, and more particularly, toAurantiochytrium sp. LA3 (KCTC12685BP) having bio-oil producibility, anda method of preparing bio-oil, particularly bio-oil having a content ofan omega-3 unsaturated fatty acid of 30 wt % or more based on totalfatty acids, characterized by culturing the microalgae.

BACKGROUND ART

Unsaturated fatty acids are also called, highly unsaturated fatty acidsor poly unsaturated fatty acids (PAUF). Particularly the unsaturatedfatty acids useful to a human body are an omega-3 (ω-3) fatty acid andan omega-6 (ω-6) fatty acid, and the omega-3 fatty acid has a doublebond at the third carbon, and the omega-6 fatty acid does not have adouble bond before the sixth carbon. Representative examples of theomega-3 unsaturated fatty acid include docosahexaenoic acid (DHA) havinga carbon chain length of 22 with 6 double bonds starting from the thirdcarbon from the methyl end, and represented by “22:6n-3”,eicosapentaenoic acid (EPA) represented by “20:5n-3”, docosapentaenoicacid (DPA) represented by “22:5n-3”, α-linolenic acid represented by“16:3n-3”, and the like, which are known as very useful kinds of anomega-3 unsaturated fatty acid, and the omega-6 unsaturated fatty acidincludes arachidonic acid (ARA) represented by “20:4n-6”, and the like.

The unsaturated fatty acids as the above play a very important role in abody: it is known that the omega-3 unsaturated fatty acid preventsarteriosclerosis and a coronary heart disease, mitigates an inflammatorycondition, and delays growth of tumor cells; and the omega-6 unsaturatedfatty acid functions as a structural lipid in a human body, and also asa precursor of numerous factors in inflammation such as prostaglandin,leukotriene and oxylipin. Particularly, docosahexaenoic acid (DHA) isknown as an essential fatty acid in brain, an ocular tissue, and anervous system, particularly having an important function in developmentof eyesight and psychomotor ability of an infant, and abundant inretina, semen and a brain tissue of a human being and an animal.Particularly, DHA is an essential fatty acid constituting 60% of brainfat. The docosahexaenoic acid is known as being important for healthydevelopment of brain, eyes, and a nervous system of an infant, togetherwith arachidonic acid (ARA), and has been reported to be effective inprevention and treatment of numerous diseases ranging from cancer toarthritis, cardiovascular diseases, and mental disorders, and recently,its various anti-aging functions such as suppression of maculardegeneration of presbyopia have been newly discovered.

Since such omega-3 or omega-6 unsaturated fatty acid has an importantfunction in a human body, it is recommended by the World HealthOrganization (WHO) that omega-3 unsaturated fatty acid should accountfor 1-2% of daily energy intake, which corresponds to about 2.2 to 4.4 gbased on 2000 kcal of meal, and it is recommended by certifiedorganizations in each country to consistently take 1 g or more of DHA aday. Therefore, DHA has been commercialized as various products such ashealth functional food, and also has high potential as pharmaceuticalraw materials, and thus, it can be said that the commercial value of DHAis very high.

However, since such omega-3 or omega-6 unsaturated fatty acid is notnaturally synthesized in a human body, there is a difficulty that thosefatty acids should be ingested mainly through food.

Previously, the omega-3 or omega-6 unsaturated fatty acid has beeningested through vegetable oil, marine animal oil, fish oil, oilseeds,and the like, and representatively has been supplied by direct ingestionof fish oil contained in fish. The fish containing a high content of EPAand DHA is mackerel, herring, salmon, and the like, and some fish suchas cod and haddock reserves most of fat in liver. Nevertheless, the bestsource is cold water fish such as tuna, mackerel, sardines, herring andtrout. However, in order to efficiently receive DHA from fish oil, it ispreferred to eat raw or boiled fish, and moreover, it is necessary toeat peel in rear gill of dorsal circumference and along abdomen, becausemost of oil is accumulated in those parts. However, since fish oildecays rapidly, and decayed fish smells fishy odor, it has adisadvantage of not whetting appetite very much, and has a seriouspollution problem by heavy metals and organic chemical materials of thefish oil. Particularly, in order to obtain fish oil in a sufficientamount to a human body, a large amount of fish is needed, and thus,practically, it is very difficult to meet such requirements economicallyon an industrial scale.

In order to solve these problems, research of a method of preparingomega-3 unsaturated fatty acid including docosahexaenoic acid byculturing various microorganisms including algae has proceeded.Particularly, interest in fine-heterotrophic bacteria calledThraustochytrid has been increased, which are a non-photosyntheticheterotrophic microorganism group classified into Stramenophila kingdomtogether with oomycetes and labyrinthulids. Thraustochytrid includesSchizochytrium, Aurantiochytrium and Thraustochytrium genera, and thespecies constituting those genera have been spotlighted as a potentialomega-3 source for industrial use, due to their high lipid content andhigh level of DHA. Thraustochytrid is a saprobe, or in some cases, atrivial name of fine heterotrophic bacteria supplied as a saprophyte.Thraustochytrid has wide geographical distribution together with strainseparated from the Antarctic Continent, the North Sea, India, Japan andAustralia. It is rarely found in living plants, and appears to beinhibited by plant antimicrobials. The species constituting this groupare abundant sometimes in a dead autochthonous organism ofindigenousness macro-algae, aquatic Mangrove leaves and the like, aswell as allochthonous plant materials. They are present usually in watercolumn including coast and deep sea, and in a deposit.

A preparation method of omega-3 unsaturated fatty acid byThraustochytrium and Schizochytrium genera microorganisms which are akind of marine microalgae has been already known since the late 1960s(Ellenbogen B. B. et al., Comp. Biochem. Physiol., 29:805-811, 1969),and Martek which is estimated to have the most advanced technology hasdeveloped a method of producing omega-3 unsaturated fatty acid usingSchizochytrium sp. ATCC 20888 and Schizochytrium sp. ATCC 20889 whichare microorganisms of a Schizochytrium genus (U.S. Pat. Nos. 5,130,242Band 5,340,742B). In addition, Suntory has reported Schizochytriumlimacinum SR21 as a microorganism having excellent docosahexaenoic acidproductivity (Japanese Patent Laid-Open Publication No. 1997-000284A,and U.S. Pat. No. 6,582,941B).

There are still a number of researches in progress, however, a demandfor new microalgae having high productivity and process efficiency, andparticularly an ability to environmentally friendly mass-produce bio-oilis urgent.

Accordingly, the present inventors exerted all efforts to developmicroalgae having high unsaturated fatty acid producibility, whilehaving high efficiency of a culture process, and as a result, confirmedthat microalgae of a Thraustochytrid were separated from a coastalwetland or a hot springs area wetland having a high temperature and richin organic materials, and in case of using the microalgae, omega-3 andadditionally omega-6 unsaturated fatty acids may be efficiently andeconomically produced, and thus, completed the present invention.

SUMMARY OF THE INVENTION

An object of the present invention is to provide microalgae having highunsaturated fatty acid productivity, and improving efficiency of aculture process, thereby allowing bio-oil to be prepared economically.

Another object of the present invention is to provide a method ofpreparing bio-oil using the microalgae.

In order to achieve the above objects, the present invention providesmicroalgae, Aurantiochytrium sp. LA3 (KCTC 12685BP) having bio-oilproducibility.

Further, the present invention provides a method of preparing bio-oil,the method comprising the steps of: (1) culturing the microalgaeAurantiochytrium sp. LA3 (KCTC 12685BP); and (2) extracting andseparating bio-oil containing omega-3 unsaturated fatty acid from thecultured microalgae.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a microphotograph of the microalgae, Aurantiochytrium sp. LA3(KCTC12685BP) of the present invention; and

FIG. 2 is a graph representing bio-oil yields, productivities, and DHAfractions in total fatty acids with culturing time of seven microalgaecolonies separated in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the present invention, in order to develop microalgae having highunsaturated fatty acid producibility, microalgae of a Thraustochytridhas been separated from a coastal wetland or a hot springs area wetlandhaving a high temperature and rich in organic materials.

Therefore, in one aspect, the present invention relates to microalgaeAurantiochytrium sp. LA3 (KCTC 12685BP) having bio-oil producibility.

The microalgae of the present invention, Aurantiochytrium sp. LA3(KCTC12685BP) is the microalgae of a Thraustochytrid, and has omega-3and omega-6 unsaturated fatty acid producibility.

The microalgae of the present invention is microalgae separated fromfloating matter in a coastal wetland or a hot springs area wetland, andmay have a DNA sequence of a 18S rRNA gene indicated as SEQ ID NO: 1. Asa result of search by NCBI (National Center for BiotechnologyInformation) Blast, it was found to be novel microalgae of aThraustochytrium family, and deposited in a gene bank of KoreanCollection for Type Cultures, Korea Research Institute of Bioscience andBiotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806,Republic of Korea as Aurantiochytrium sp. LA3, Accession No. KCTC12685BPon Sep. 26, 2014.

The bio-oil prepared by Aurantiochytrium sp. LA3 (KCTC12685BP) accordingto the present invention may have a content of an omega-3 unsaturatedfatty acid of 30 wt % or more based on total fatty acids.

Aurantiochytrium sp. LA3 (KCTC12685BP) provided by the present inventionhas advantages of having a rapid sugar consumption rate when beingcultured using glucose as a carbon source, having a high oil content,and allowing cells to be cultured at a high concentration, therebyobtaining oil in high productivity and a high yield.

In another aspect, the present invention provides a method of preparingbio-oil, the method comprising the step of: (1) culturing the microalgaeAurantiochytrium sp. LA3 (KCTC 12685BP); and (2) extracting andseparating bio-oil containing omega-3 unsaturated fatty acid from thecultured microalgae.

In the present invention, culturing in above step (1) may be carried outin a manner selected from the group consisting of batchwise,fed-batchwise, and continuous culturing, and in above step (2), a celldisruption step may be further included.

The cell disruption may be cell disruption using a supersonic disperser,cell disruption using a pulsed electric field, cell disruption using anenzyme, cell disruption using osmotic pressure, cell disruption using anelectron beam, or cell disruption using an organic solvent.

The method of preparing bio-oil of the present invention may furthercomprise (3) purifying bio-oil containing the omega-3 fatty acid.

In the present invention, the purification may include collecting onlyan oil phase among an oil phase containing bio-oil and an aqueous phasecontaining cell pieces, and may be carried out by including one or moresteps of removing a solidified oil fraction, bleaching using bleachingclay or activated carbon, filtering, and deodorizing.

In the present invention, the deodorizing step may be carried out by asteam deodorizing process under reduced pressure.

In one embodiment of the present invention, the method of preparingbio-oil containing omega-3 fatty acid using the Aurantiochytrium sp. LA3(KCTC12685BP) may comprise the following steps:

(1) culturing Aurantiochytrium sp. LA3 (KCTC12685BP); and

(2) collecting the cultured Aurantiochytrium sp. LA3 (KCTC12685BP), andextracting and separating bio-oil containing omega-3 unsaturated fattyacid.

The method may further comprise:

(3) purifying bio-oil containing the separated omega-3 unsaturated fattyacid.

Hereinafter, each step will be described in detail.

Culturing of Aurantiochytrium sp. LA3 (KCTC12685BP) in above step (1)may proceed in a manner selected from batchwise, fed-batchwise andcontinuous culturing, and it is preferred to use fed-batchwise orcontinuous culturing.

In step (1) , it is preferred to supply a carbon source for culturingAurantiochytrium sp. LA3 (KCTC12685BP) through the fed-batchwise orcontinuous culturing. Herein, the carbon source may be used withoutlimitation only if it grows using Aurantiochytrium sp. LA3(KCTC12685BP), and glucose, fructose, sucrose, galactose, glycerol,crude glycerol which is biodiesel waste, and the like are preferred, butnot limited thereto, and glucose is most preferred. It is preferred thatthe carbon source is supplied in a continuous or fed-batchwise manner soas to maintain proper concentration, and if necessary, a method such aspH-stat or DO-stat may be used, and a method of supplying the carbonsource as required by measuring the concentration of each carbon sourcein real time, and the like may also be used. In addition, a nutrientneeded for growth of Aurantiochytrium sp. LA3 (KCTC12685BP) may becontained in a medium, and it is apparent to a person skilled in the artthat a variety of a nitrogen source, a phosphate source, othercomponents, and the like may be contained, and also a complex medium, adefined medium, or the like may be used. As the nitrogen source, anorganic nitrogen source such as yeast extract, corn steep liquor, beefextract, malt extract, peptone, tryptone, and the like, and an inorganicnitrogen source such as acetate, ammonium nitrate, ammonium sulfate,sodium nitrate, urea, and the like may be used.

Particularly, it is preferred to set salt concentration to anappropriate concentration level and proceed with culturing within therange.

In step (1), it is preferred to maintain pH and/or temperature within apredetermined range, during culturing Aurantiochytrium sp. LA3(KCTC12685BP) through fed-batchwise or continuous culturing. As the wayto constantly maintain pH and/or temperature during culturing, awell-known method in the art, such as a method of using a cooling jacketwith cooling water, a method of using a pH controller to automaticallysupply acid or base, and the like, may be used, but not limited thereto.

Further, it is preferred that culturing of Aurantiochytrium sp. LA3(KCTC12685BP) through the fed-batchwise or continuous culturing, iscarried out under adequate aeration and agitation. An aeration speed andan agitation speed may be appropriately selected by a person skilled inthe art according to a process condition. More specifically, sinceAurantiochytrium sp. LA3 (KCTC12685BP) is aerotropic, and has a propertyof being weak under shear stress by agitation, it is preferred thatagitation speed may be selected from 50-300 rpm, preferably 100-300 rpm,and aeration speed may be 0.5-5 vvm, preferably 1-3 vvm.

The content of an omega-3 unsaturated fatty acid in the bio-oil producedthrough culturing of step (1) according to the present invention is 30wt % or more, preferably 40 wt % or more, most preferably 50 wt % ormore, based on total fatty acids.

The step to collect the cultured Aurantiochytrium sp. LA3 (KCTC12685BP),and extract and separate bio-oil containing an omega-3 unsaturated fattyacid according to step (2), includes a step to disrupt cells, aftercompleting the culturing in step (1). In the step of cell disruption,cell disruption may be induced by methods of cell disruption using apulsed electric field, cell disruption using an enzyme, cell disruptionusing an electron beam, and the like, but not limited thereto, and it isapparent to a person skilled in the art that a method of using anorganic solvent such as hexane to disrupt cells and extract oil, may beused. Particularly, if the disruption technique is used after celldisruption using osmotic pressure, a cell disruption effect may beenhanced.

As the cell disruption proceeds, phase separation of an oil phase and anaqueous phase containing cell pieces occurs, and only the oil phase iscollected at this time, and a final bio-oil product may be obtainedthrough a purification process in step (3).

The purification of bio-oil according to step (3) is carried out byincluding one or more steps selected from the group consisting ofleaving the oil phase at −5-0° C. for 5-20 hours to remove a solidifiedoil fraction, bleaching the oil fraction using bleaching clay and/oractivated carbon, filtering, and deodorizing, and preferably, thosesteps may be sequentially carried out.

It is preferred to carry out filtering using a filter having a pore sizeof 0.5-1 μm, and it is also preferred to carry out deodorizing through asteam deodorization process under reduced pressure, but not limitedthereto.

Hereinafter, the present invention will be described in detail throughthe following Examples. These Examples are only for specificallyillustrating the present invention, and it is apparent to a personskilled in the art that according to the gist of the present invention,the scope of the present invention is not limited to these Examples.

EXAMPLE 1 Separation of Microalgae

In order to screen microalgae having excellent bio-oil producibility,microalgae of a Thraustochytrid family were separated from floatingmatters in a coastal wetland or a hot springs area wetland, in thefollowing manner.

A sample of floating matters was added to 50 mL of a medium containing10 g/L of glucose, 2 g/L of yeast extract, 2 g/L of peptone, 1 g/L ofKH₂PO₄, and 30 g/L of sea salt, and cultured for a day. 50 mL of theobtained culture fluid was smeared on a solid medium containing 10 g/Lof glucose, 2 g/L of yeast extract, 2 g/L of peptone, 1 g/L of KH₂PO₄,30 g/L of sea salt and 15 g/L of agar, and thereafter, cultured at 28°C. for 5 days to obtain seven colonies, and the obtained seven colonieswere subcultured 4 times to be purely separated.

Each of the colonies was cultured in a 50 mL shaking incubator at 28° C.for 4 days at 150 rpm using 5 mL of a liquid medium (glucose 60 g/L,corn steep liquor 14.4 g/L, sea salt 10 g/L, potassium phosphatemonobasic 1 g/L, glutamic acid 3 g/L, sodium sulfate 5 g/L, ammoniumsulfate 1 g/L, calcium chloride 0.4 g/L, magnesium sulfate 2 g/L, ferricsulfate 1 mg/L, zinc sulfate 1 mg/L, manganese(II) chloride 3 mg/L,cobalt(II) chloride 0.04 mg/L, sodium molybdate 0.04 mg/L, copper(II)sulfate 2 mg/L, nickel(II) sulfate 2 mg/L, and thiamin 1 mg/L), culturedin a 250 mL shaking incubator at 28° C. for 3 days at 150 rpm using 50mL of the liquid medium, cultured in a 1000 mL shaking incubator at 28°C. for a day at 150 rpm using 400 mL of the liquid medium, andthereafter, cultured in a 5 L jar fermentor at 28° C., 200 rpm, 0.7 vvmand initial pH 7.0 using 2 L of the liquid medium. Cultured microbialcells were collected, respectively, and subjected to disruption with asupersonic disruptor, and oil was extracted with 100 mL of hexanetherefrom, and thereafter, the extracted oil was analyzed for fatty acidcompositions in the oil with an AOCS (American Oil Chemists' Society)method.

Among the separated seven colonies, a microbial cell #4 having thehighest oil producibility and yield, and containing 30 wt % or more ofan omega-3 fatty acid in total fatty acids was screened (FIGS. 1 and 2).

EXAMPLE 2 Identification Through 18S DNA Analysis

For molecular biological identification of the finally screened strain#4, a 18S rRNA gene sequence was analyzed. After chromosomal DNA wasseparated from one colony, 18S rRNA gene DNA was amplified by a PCRmethod, using primers for amplification of a 18S rRNA gene of microalgaeof a Thraustochytrid family, F: 5'-AACCTGGTTGATCCTGCCAG-3' (SEQ ID NO:2) and R: 5'-TTGTTACGACGACTTCACCTTCCT-3' (SEQ ID NO: 3). After removinga salt, an amplified reaction solution was analyzed by MacrogenCorporation for a base sequence, and the sequence was identified as SEQID NO: 1. As a result of search through NCBI (National Center forBiotechnology Information) Blast, the screened strain was found to benovel microalgae of a Thraustochytrium , and deposited in a gene bank ofKorean Collection for Type Cultures as Aurantiochytrium sp. LA3(KCTC12685BP) on Sep. 26, 2014.

EXAMPLE 3 Analysis of Growth and Bio-Oil Production Characteristics ofAurantiochytrium sp. LA3 (KCTC12685BP) Under Batchwise Culture Condition

Growth and bio-oil production characteristics of microalgae,Aurantiochytrium sp. LA3 (KCTC12685BP) separated from Example 1 wereresearched and analyzed under a batchwise culture condition.

Single Aurantiochytrium sp. LA3 (KCTC12685BP) colony cultured in a solidmedium was selected, and cultured at 28° C. for 4 days at 150 rpm, using5 mL of a liquid medium {(glucose g/L, yeast extract 4.8 g/L, potassiumchloride 1 g/L, potassium phosphate monobasic 2 g/L, glutamic acidsodium salt 3 g/L, sodium sulfate 12 g/L, calcium chloride 0.5 g/L,magnesium sulfate 2 g/L, trace elements (ethylenediaminetetraacetic acid18 mg/L, ferric sulfate 0.87 mg/L, boric acid 20.52 mg/L, zinc sulfate0.711 mg/L, manganese(II) chloride 2.58 mg/L, cobalt(II) chloride 0.078mg/L, sodium molybdate 0.015 mg/L, copper(II) sulfate 0.006 mg/L,nickel(II) sulfate 0.156 mg/L), and vitamins (thiamin 0.6 mg/L, biotin0.0015, cobalamin 0.015 mg/L, calcium pantothenate 0.6 mg/L)}, culturedat 28° C. for 3 days at 150 rpm, using 50 mL of the liquid medium,cultured at 28° C. for a day at 150 rpm, using 400 mL of the liquidmedium, and thereafter, batch-cultured in a 5 L fermentor at 28° C., 200rpm, 0.7 vvm, and initial pH 7.0, using 2 L of a liquid medium (glucose120 g/L, corn steep liquor 28.8 g/L, potassium chloride 1 g/L, potassiumphosphate monobasic 2 g/L, glutamic acid sodium salt 3 g/L, sodiumsulfate 12 g/L, calcium chloride 0.5 g/L, magnesium sulfate 2 g/L, traceelements, and vitamins). Cultured microbial cells were collected,respectively, and subjected to disruption with a supersonic disruptor,and oil was extracted with 100 mL of hexane therefrom, and thereafter,the extracted oil was analyzed for fatty acid compositions in the oilwith an AOCS (American Oil Chemists' Society) method.

As a result, all glucose in the medium was consumed in 36 hours, and49.7 g/L of microbial cells were obtained at this time (Table 1). As aresult of extracting oil in microalgae from the obtained microbialcells, an oil content relative to a dry weight of microalgae was 51.2 wt%, and a DHA content relative to fatty acids was 33.6 wt %.

TABLE 1 Cell density Oil content DHA(% (g/L) (%) FAME) yieldproductivity 49.7 ± 5.4 51.2 ± 7.5 33.6 ± 2.9 20.7 ± 3.1 17.0 ± 3.0

EXAMPLE 4 Analysis of Growth and Bio-Oil Production Characteristics ofAurantiochytrium sp. LA3 (KCTC12685BP) Under Fed-Batchwise CultureCondition

Growth and bio-oil production characteristics of microalgae,Aurantiochytrium sp. LA3 (KCTC12685BP) separated from Example 1 wereresearched and analyzed under a fed-batchwise culture condition.

Single Aurantiochytrium sp. LA3 (KCTC12685BP) colony cultured in a solidmedium was selected, and cultured at 28° C. for 4 days at 150 rpm, using5 mL of a liquid medium {(glucose g/L, yeast extract 4.8 g/L, potassiumchloride 1 g/L, potassium phosphate monobasic 2 g/L, glutamic acidsodium salt 3 g/L, sodium sulfate 12 g/L, calcium chloride 0.5 g/L,magnesium sulfate 2 g/L, trace elements (ethylenediaminetetraacetic acid18 mg/L, ferric sulfate 0.87 mg/L, boric acid 20.52 mg/L, zinc sulfate0.711 mg/L, manganese(II) chloride 2.58 mg/L, cobalt(II) chloride 0.078mg/L, sodium molybdate 0.015 mg/L, copper(II) sulfate 0.006 mg/L,nickel(II) sulfate 0.156 mg/L), and vitamins (thiamin 0.6 mg/L, biotin0.0015, cobalamin 0.015 mg/L, calcium pantothenate 0.6 mg/L)}, culturedat 28° C. for 3 days at 150 rpm, using 50 mL of the liquid medium,cultured at 28° C. for a day at 150 rpm, using 400 mL of the liquidmedium, and thereafter, fed-batch-cultured in a 5 L fermentor at 28° C.,250 rpm, 0.7 vvm, and initial pH 7.0, using 1 L of a liquid medium(glucose 60 g/L, corn steep liquor 14.4 g/L, potassium chloride 1 g/L,potassium phosphate monobasic 2 g/L, glutamic acid sodium salt 3 g/L,sodium sulfate 12 g/L, calcium chloride 0.5 g/L, magnesium sulfate 2g/L, trace elements, and vitamins). When a residual amount of sugar is10-20 g/L, 420 g/L of glucose was fed twice by 0.5 L to finally obtain2L of a culture fluid. Cultured microbial cells were collected,respectively, and subjected to disruption with a supersonic disruptor,and oil was extracted with 100 mL of hexane therefrom, and thereafter,the extracted oil was analyzed for fatty acid compositions in the oilwith an AOCS (American Oil Chemists' Society) method.

As a result, all glucose in the medium was consumed in 60 hours, and109.9 g/L of microbial cells were obtained at this time (Table 2). As aresult of extracting oil in microalgae from the obtained microbialcells, an oil content relative to a dry weight of microalgae was 60.2 wt%, and a DHA content relative to fatty acids was 30.7 wt %.

TABLE 2 Cell density Oil content DHA(% (g/L) (%) FAME) yieldproductivity 109.9 ± 3.0 60.2 ± 1.2 30.7 ± 1.3 24.2 ± 0.2 26.4 ± 0.2

The microalgae Aurantiochytrium sp. LA3 (KCTC12685BP) according to thepresent invention has a rapid sugar consumption rate when being culturedusing glucose as a carbon source, has a high oil content, allows cellsto be cultured at a high concentration, and allows oil to be obtained inhigh productivity and a high yield, and thus, may produce bio-oil moreeconomically and environmentally friendly.

The present invention has been described in detail in specific parts,and it is obvious that such specific technique is only a preferredembodiment to a person skilled in the art, without limiting the scope ofthe present invention thereby. Thus, the substantial scope of thepresent invention will be defined by the appended claims and theirequivalents.

1. A microalgae Aurantiochytrium sp. LA3 (KCTC 12685BP) having bio-oilproducibility.
 2. The microalgae of claim 1, wherein theAurantiochytrium sp. LA3 (KCTC 12685BP) has a DNA sequence of a 18S rRNAgene of SEQ ID NO:
 1. 3. The microalgae of claim 1, wherein bio-oilprepared from the microalgae has an omega-3 unsaturated fatty acidcontent of 30 wt % or more based on total fatty acids.